Process for the Treatment of a Hydrophobic Surface by an Aqueous Phase

ABSTRACT

The invention relates to process for the treatment of a hydrophobic surface by a liquid film comprising an aqueous phase comprising the coating of said surface by the liquid whose aqueous phase comprises an effective amount of an agent of modification of the properties of surface and an active agent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.12/294,178, filed Jun. 15, 2009, which is the U.S. National Phase ofInternational Application No. PCT/EP2007/052774 filed on Mar. 22, 2007,which claims priority to U.S. Provisional Application No. 60/785,289,filed Mar. 23, 2006, the subject matters of which are incorporated byreference herein in their entireties.

FIELD OF THE INVENTION

The present invention relates to a process for the treatment of ahydrophobic surface by means of a liquid film containing an aqueousphase including an agent for the modification of the properties of thehydrophobic surface. The liquid film is typically a solution containingwater, a partially water soluble organic compound that spontaneouslyforms a film at the water-surface interface and an agent for themodification of the properties of the hydrophobic surface.

SUMMARY OF THE INVENTION

One of the goal of the process according to the invention is to modifythe physicochemical properties of a hydrophobic surface by an aqueousphase (such as a solution) in order to promote and facilitate treatmentsof said surface by an active agent contained in the liquid film (aqueousphase) and in particular to provide properties of hydrophilizing,wetting, soil release, sustained release of perfumes or biocides and/orimproving activity of an agent. An agent for the modification of theproperties of the hydrophobic is believed to assist in providing theabove hydrophilizing, wetting, soil release, sustained release ofperfumes or biocides and/or improving activity. The invention alsoallows reducing the amount of surfactants being used to treat surfaces(or even to avoid their use), which can be benefic for the environmentor at least perceived as benefic.

Thus, the object of the invention is a process for the treatment of ahydrophobic surface by a liquid film comprising an aqueous phase, saidprocess comprising the coating of said surface by the liquid whoseaqueous phase comprises an effective amount of an agent of modificationof the properties of surface and an active agent.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In one fashion, the aqueous phase of the liquid of treatment (such as asolution) comprises an agent for the modification of the hydrophobicproperties of surfaces (AMHPS) is a substance, polymer or molecule:

suitable for spontaneously form a film nanometric on the interface waterof the aqueous phase/hydrophobic surface;

partially water soluble, this solubility in water being lower than 1%and higher than 0.001%;

having a relative permittivity ({acute over (ε)}r) lower than 80 andhigher than that of the hydrophobic surface to treat or a refractiveindex greater than 1.33 and lower than that of the hydrophobic surface;

having a surface tension water/agent ranging between 5 mN/m and 50 mN/m;and

being in a liquid state at ambient temperature with a viscosity rangingfrom 1 mPA·s to 100 mPa·s.

The liquid of treatment (such as the solution) can comprise water, theagent (henceforth called AMHPS) that is capable of spontaneously forminga film at the water-substrate interface and an active material,preferably a surface active material that adsorbs at the interface ofthe liquid and the surface.

The liquid film according to the invention can be a liquid compositionapplied to the surface to be treated, let to dry, or rinsed.

According to the invention, an effective amount of AMHPS can rangebetween 5% and 95% of the maximum solubility concentration of the AMHPSagent in water.

Generally speaking, the AMHPS agent can be a substance, eitherelectrically neutral, or charged. It can also be a mixture of moleculesor substances corresponding to the characteristics described above. Inparticular, it can be a mixture of charged molecules and neutralmolecules, preferentially containing a small fraction of chargedmolecules, lower than 10% in number.

The AMHPS agents can assist in improving the effectiveness of thesurface treatments. For example it can assist in the delivery and/orretention of the surface active agents at the interface. The surfaceactive agents may impart properties such as hydrophilicity, staticdischarge, catalysis, UV-absorption, photoluminescence, anti-fouling orextended release of substances such as perfumes or biocides to thetreated interface.

The improvement of the effectiveness can be judged by obtainingidentical performances with a smaller rate of active agent providing theaforementioned properties or by a greater durability of the soughteffect, for example by a resistance to a higher number of rinsings ofthe treated hydrophobic surface. The effectiveness of AMHPS agents indelivering surface active agents to an interface can be inferred by thedirect comparison of a specific surface property such as wetting of asurface that has been treated with a solution containing an AMHPS tothat of a surface treated with a solution not containing the AMHPS.

Without limiting the scope of the invention to a particular scientifictheory, it is possible to explain the operating mode of the AMHPS in thefollowing way: Because of their relative permittivity or, moreprecisely, their Hamaker constants and their surface tensions, theAMHPS, when they are present in the aqueous phase of treatment at aconcentration lower or equal to the maximum solubility concentration,spontaneously form a liquid film which is a few nanometers thick on thesurface. There the Hamaker constant of the AMHPS preferably rangesbetween that of the substrate and that of water. The formation of theliquid film of AMHPS is generally very fast, generally about a few tensof milliseconds, which makes the treatment compatible with theindustrial processes.

The thickness of the liquid film usually depends on the AMHPSconcentration. This film can be very thick, higher than 10 nm(nanometer) if the AMHPS concentration is that of the maximum solubilitylimit. If the concentration is lower, the film gets thinner as thedifference with the maximum solubility concentration becomes moreimportant. This liquid film is formed spontaneously and its formation isnot affected by the presence of the other ingredients of the formulationsuch as polymers and surface-active agents.

Due to the fact that the AMHPS film is only a few nanometers thick, itis possible to treat a solid substrate with an aqueous solution thatcontains a few parts per million (ppm) of AMHPS.

In order to enhance the delivery of surface active components to aninterface in the presence of AMHPS, the aqueous phase may be modified bythe addition of an organic or inorganic electrolyte salt havingmonovalent or multivalent anions and/or cations preferably present in aconcentration lower than 0.1 Wt % and preferably higher than 0.001 Wt %of the total weight of the aqueous phase. Suitable cations may bemonovalent or multivalent, may be organic or inorganic, and include, forexample, sodium, potassium, lithium, calcium, magnesium, cesium, andlithium cations, as well as mono-, di- tri- or quaternary ammonium orpyridinium cation. Suitable anions may be a monovalent or multivalent,may be organic or inorganic, and include, for example, chloride,sulfate, nitrate, nitrite, carbonate, citrate, cyanate acetate,benzoate, tartarate, oxalate, phosphate, and phosphonate anions.Suitable electrolytes include, for example, salts of multivalent anionswith monovalent cations, such as potassium pyrophosphate, potassiumtripolyphosphate, and sodium citrate, salts of multivalent cations withmonovalent anions, such as calcium chloride, calcium bromide, zinchalides, barium chloride, and calcium nitrate, and salts of monovalentcations with monovalent anions, such as sodium chloride, potassiumchloride, potassium iodide, sodium bromide, ammonium bromide, alkalimetal nitrates, and ammonium nitrates. Preferred salts are NaNO₃, KNO₃,KCL, NaCl, NH4NO₃, or NH₄Cl.

The formation of the liquid film of AMHPS is generally very fast,generally about a few tens of milliseconds, which makes the treatmentcompatible with the industrial processes.

The formation of film is initially influenced by the physical nature ofthe material constitutive of the hydrophobic surface to treat anddepends less upon the chemical nature of that surface and, thus, badlyglossy or badly cleaned surfaces can be treated in a similar way.

The AMHPS agents can be selected for example in the family of mono, dior tri ester of phosphates, more particularly among those of thefollowing formula (I):

O═P(OR₁)(OR₂)(OR₃)  (I)

wherein,R₁, R₂, and R₃, identical or different are:

a hydrogen atom, or

a radical alkyl saturated or unsaturated, linear or ramified or cyclic,having from 1 to 22 atoms of carbon, preferably from 2 to 12 atoms ofcarbon, and even more preferably from 2 to 8 carbon atoms, optionallysubstituted by halogen atoms, such as fluorine or chlorine, hydroxylgroups, ether groups having between 1 and 12 carbon atoms, preferablybetween 1 and 6 carbon atoms, thioether groups, ester groups, amidegroups, carboxy group, acid sulphonic groups, anhydride carboxylicgroups, and/or carbonyl groups, or—an aryl radical, having from 6 to 22atoms of carbon, preferably from 6 to 8 carbon atoms, optionallysubstituted by halogen atoms, such as fluorine or chlorine, hydroxylgroups, ether groups having between 1 and 12 carbon atoms, preferablybetween 1 and 6 carbon atoms, thioether groups, ester groups, amidegroups, carboxy group, acid sulphonic groups, anhydride carboxylicgroups, and/or carbonyl groups, and

at least one of R₁, R₂ or R₃ is different from a hydrogen atom.

Some examples of mono, di or tri ester of phosphates, may be:

-   -   tris(2-ethylhexyl) phosphate,    -   tris(2-butoxyethyl) phosphate,    -   di(2-ethylhexyl) phosphate,    -   mono(2-ethylhexyl) phosphate,    -   tris(2-isooctyl) phosphate,    -   tricrésylphosphate,    -   crésyldiphénylphosphate,    -   trixylilphosphate,    -   triphénylphosphate,    -   tributyl phosphate,    -   triethyl phosphate,    -   tri(2chloroethyl)phosphate, or their mixtures.

The mono, di or tri phosphate ester of the agent according to theinvention can be also built-in in a liquid form or in the form of asolid powder in a composition of film forming polymer insoluble in wateror in a phyto, detergent or cosmetic composition comprising an aqueousphase. If the mono, di or tri phosphate ester of the invention ispresented in a liquid form at ambient temperature, as it is the case ofthe particular compounds listed above except for the triphenylphosphatewhich is solid at ambient temperature, it is possible to adsorb them onan inert mineral support to obtain a solid powder. A preferred mode ofembodiment to prepare the solid powder of mono, di or tri esters ofphosphate is a process comprising the step of dry impregnating a mineraloxide by a sufficient quantity of the mono, di or tri esters ofphosphate.

Agents AMHPS can be for example also selected in the family of organicesters including esters of vegetable or animal origin, or esters themono-di or triglyceride, partially hydrolyzed, alcohols with limitedsolubility in water, non-polar organic solvents such as cyclohexane,aromatic solvents such as toluene, chlorinated solvents such aschloroform, and vinyl pyrolidone.

Preferred esters are compounds of the following formula (II):

R1-C(═O)—O—R2  (II)

wherein the radicals R1 and R2 have the same meaning as in formula (I)above.

Surface active agents used in the formulation may include mineral oxidenanoparticles, polymeric latexes, ionic or non ionic surfactants,neutral or charged polymers, supramolecular assemblies of polymers ormixtures of the above materials.

Examples of mineral oxides include silica, alumina, silica-alumina,silico-aluminate of sodium, calcium silicate, magnesium silicate,zirconia, magnesium oxide, calcium oxide, cerium oxide or titaniumoxide. The mineral oxide can be totally or partially hydroxylated orcarbonated. The mineral oxide may have a large surface area. Thepreferred mineral oxide is a silica, in a way even more preferential anamorphous silica. That one can be a natural silica or a synthetic silicalike silica gels, fumed silicas or, in a very preferred way,precipitated silicas. The mineral particles may also be impregnated withadditives such as fragrances, pesticides or drugs. Additionally, themineral oxide particles as well as latex particles may themselves beimpregnated by the AMHPS.

The liquid composition of treatment can be an aqueous film formingpolymer dispersion (latex) in post-polymerization. Then, optionally, thelatex can be dried out on the treated hydrophobic support. The mono, dior tri ester of phosphate can be added directly to the liquidcomposition of treatment, in an amount ranging between 0.01 and 5% indry weight of mono, di or tri ester of phosphate, preferably between0.02 and 1%, based on the total weight of the composition. This activeagent can be a molecule, substance or polymer conferring a functionparticular to the composition. The active agents can be associativewater-soluble polymers, water-soluble zwiterionic polymers, amphotericwater-soluble polymers, water-soluble polymers having a cationic charge.These active agents can be for example surface-active agents, mineralparticles, organic like dyes or perfumes, having a modifying action ofthe wettability (hydrophilization or hydrophobization) or providingsoil-release properties. These active agents associated with the AMHPSagents, present an upgraded action. The active substances such asperfume, biocide, insecticide, softener, can be delivered by the AMHPSagents which more effectively transport them towards the hydrophobicsurface to treat.

AMHPS can have a direct role in delivering an active molecule to asurface whenever that agent, a perfume for example, has a highersolubility in the AMHPS agents than in water. In this case, the liquidfilm of the AMHPS agents is used as a source for the active agent. TheAMHPS agents can be carried not only by a latex or a mineral oxide, suchas silica particles, but also via an emulsion, of a lamellar phase ormicrogels. Another aspect of the invention making it possible to benefitfrom the ability of the AMHPS agents to form a liquid film in thevicinity of a damaged surface (damaged hair, striped surface). Capillaryforces at these surfaces can then be exploited to reinforce theadsorption of the surface active species such as nanoparticles orlatexes to heal the defects on the surface. There can be mechanisms oftransport of the species adsorbed on the surface (of the particles,polymers) which make it possible to reinforce adsorption on the level ofthe defect. That can make it possible to make a curative treatment whichwould selectively target the defect (healing treatment).

One embodiment of the present invention is the use of a water solubleAMHPS agent that vitrifies upon the evaporation of water. Such an agentwill provide a mechanically resistant film of adsorbed materials at thesurface. It is possible to consider partially water soluble AMHPS agentsbut presenting a vitreous transition upon drying. Thus, after drying theformulation, the liquid film would thus become solid and, thus,mechanically more resistant.

The hydrophobic surfaces to be treated are for example made ofpolyesters, PVC, polyethylenterphtalate, polycarbonate, polyamides, orpolyolefins such as polyethylene and polypropylene. These surfaces canbe hair, human skin, human hair, natural or synthetic fibers, crockery,metal objects, glass or ceramics. The surface can be different frompolystyrene. The liquid is typically different from a liquid having ahydraulic binder (such as cement, plaster, concrete etc).

The treatment of the invention can be applied for example in home hardsurface care, industrial or institutional cleaning for example of hardsurfaces, personal-care, laundry, fibers and/or fabric industrialtreatments.

BRIEF DESCRIPTION OF THE FIGURES

The invention is further illustrated in the following examples.Reference is made to the enclosed drawing wherein:

FIG. 1 is a chart showing the adsorption kinetics of cerium oxidenanoparticles onto HMDS coated silicon substrates, and

FIG. 2 is a chart showing the receding contact angles of water onpolypropylene surfaces treated with cerium oxide solutions containingorganic solvents.

EXAMPLE 1

Silicon (refractive index: 1.46) modified by treatment withhexamethylene disilazane (HMDS) is used as the first surface. Thereceding contact angle of water on the silicon surface is 69 degrees.This surface is treated by immersion in a 0.1 wt % aqueous suspension ofcerium dioxide nanoparticles having a diameter of 10 nm at pH of 1 forover 2 hours and then rinsed to remove any unadsorbed nanoparticles.After drying, the receding contact angle of water on the treated surfaceis measured. The receding contact angle of water on the treatedsubstrate had reduced from 69 degrees to 53 degrees.

To enhance the adsorption of cerium oxide nanoparticles, n-butyl acetateused as the as the AMHPS having a refractive index: 1.394 at aconcentration of 0.63 wt % is added to an aqueous solutions containing0.1 wt % cerium oxide at pH 1.5. Then, a HMDS treated silicon substrateis immersed in this solution for over two hours and treated as describedabove. The receding contact angle of water on the treated surface isthen measured. The value of the receding contact angle is 45 degrees.The results are gathered in the table 1 below:

TABLE 1 Contact angles with water Surface treated with the Surfacetreated with the active in the presence of Untreated surface active only(nano-CeO2) AMHPS (n-butyl acetate) 69 deg. 53 deg. 45 deg.

This reduction in the receding contact angle occurs due to enhancedadsorption of the cerium oxide nanoparticles in the presence of awetting film of the added co-solvent on the hydrophobic polymer surface.

To prove the hypothesis of enhanced adsorption, the kinetics ofadsorption of the nanoparticles are measured by light reflectancespectroscopy using the technique disclosed by Dijt, J. C.; Cohen Stuart,M. A.; Fleer, G. J.; “Reflectometry as a tool for adsorption studies”;Adv. Colloid. Interface. Sci. 1994, 50, 79.

The results of these measurements, which are plotted in FIG. 1, indicatethat the adsorption of cerium oxide nanoparticles onto the siliconsubstrates increases by a factor of 2 due to the presence of 0.63 wt %n-butyl acetate.

EXAMPLE 2

Polycarbonate (refractive index: 1.586) plaques are used as ahydrophobic surface. The receding contact angle of water on an untreatedpolycarbonate surface is 55 degrees. This surface is treated byimmersion in a 0.1 wt % aqueous suspension of cerium dioxidenanoparticles having a diameter of 10 nm at pH of 1.5. The polycarbonateplaque is immersed in the aforementioned suspension of nanoparticles forover 2 hours and then rinsed to remove any unadsorbed nanoparticles.After drying, the receding contact angle of water on the treated surfaceis measured. The receding contact angle of water on the treatedsubstrate is 55 degrees indicating no adsorption of nanoparticles onthis surface.

To enhance the adsorption of cerium oxide nanoparticles, n-butyl acetateused as an AMHPS at a concentration of 0.63 wt % is added to an aqueoussolution containing 0.1 wt % cerium oxide at pH 1.5 A polycarbonateplaque is immersed in this solution for over two hours and treated asdescribed above. The receding contact angle of water on the treatedsurface is then measured. The value of the receding contact angle is 32degrees. The results are gathered in the table 2 below:

TABLE 2 Contact angles with water Surface treated with the Surfacetreated with the active in the presence of Untreated surface active only(nano-CeO2) AMHPS (n-butyl acetate) 55 deg. 55 deg. 32 deg.

EXAMPLE 3

Nylon 6, 6 (refractive index: 1.53) plaques are used as a hydrophobicsurface. The receding contact angle of water on an untreated nylonsurface is 53 degrees. This surface is treated by immersion in a 0.1 wt% aqueous solution of cerium oxide at pH of 1.5. The Nylon 6, 6 plaqueis immersed in the aforementioned solution for over 2 hours and thenrinsed to remove any unadsorbed nanoparticles. After drying, we measuredthe receding contact angle of water on the treated surface. The recedingcontact angle of water on the treated substrate was unchanged indicatingno adsorption of nanoparticles

To enhance the adsorption of cerium oxide nanoparticles, n-butyl acetateat a concentration of 0.63 wt is added to an aqueous solutionscontaining 0.1 wt % cerium oxide at pH 1.5 A Nylon 6,6 plaque isimmersed in this solution for over two hours and treated as describedabove. The receding contact angle of water on the treated surface isthen measured. The value of the receding contact angle is 34 degrees.The results are gathered in the table 3 below:

TABLE 3 Contact angles with water Surface treated with the Surfacetreated with the active in the presence of Untreated surface active only(nano-CeO2) AMHPS (n-butyl acetate) 53 deg. 53 deg. 34 deg.

EXAMPLE 4

Polypropylene (refractive index: 1.49) plaques are used as a hydrophobicsurface. The receding contact angle of water on an untreatedpolypropylene surface is 76 degrees. This surface is treated byimmersion in a 0.1 wt % aqueous solution of cerium oxide at pH of 1.5.The polypropylene plaque is immersed in the aforementioned solution forover 2 hours and then rinsed to remove any unadsorbed nanoparticles.After drying, the receding contact angle of water on the treated surfaceis measured. The receding contact angle of water on the treatedsubstrate had reduced from 76 degrees to 57 degrees.

To enhance the adsorption of cerium oxide nanoparticles, the followingorganic solvents are added to an aqueous solutions containing 0.1 wt %cerium oxide at pH 1.5

1. n-butyl acetate at a concentration of 0.35 wt %

2. Octanol (refractive index: 1.431) at a concentration of 0.05 wt %

3. Tris (2-butoxyethyl) phosphate (TBEP) (refractive index: 1.434)

4. Cyclohexane (refractive index: 1.426) at a concentration of 0.002 wt%

The receding contact angles of water on each of the treated surfaces areshown in the FIG. 2. This reduction in the receding contact angle occursdue to enhanced adsorption of the cerium oxide nanoparticles in thepresence of a wetting film of the added co-solvent on the hydrophobicpolymer surface.

EXAMPLE 5

Silicon oxide nanoparticles are suspended in an aqueous solution at pH3.0. This suspension is modified by the addition of 0.1M NaNO₃. Apolypropylene plaque is immersed in this solution for 2 hours. Thetreated plaque is rinsed in deionized water and air dried. The recedingcontact angle of water on the treated plaque is 47 degrees. To furtherenhance the adsorption of silicon oxide nanoparticles, 0.05 wt % Octanolis added to the solution of Silicon oxide nanoparticles at pH 3containing 0.1M NaNO₃. A polypropylene plaque is immersed in thissolution for two hours and then rinsed in deionized water and air dried.The receding contact angle of water on this substrate is found to be 21degrees. The results are gathered in the table 4 below:

TABLE 4 Contact angles with water Surface treated with the Surfacetreated with the active in the presence of active only (nano-CeO2) saltand AMHPS (n-butyl Untreated surface in the presence of salt acetate) 76deg. 47 deg. 21 deg.

The table 3 shows that a AMHPS used in combination with a highly saltedformulation provides better results.

1-16. (canceled)
 17. A process for treating a hydrophobic surface with aliquid film comprising an aqueous phase, said process comprising:coating said surface with the liquid film, wherein the aqueous phasecomprises an effective amount of an agent for the modification of theproperties of said surface and an active agent; and further wherein theagent for the modification of the properties of said surface comprises:tris(2-ethylhexyl) phosphate, tris(2-butoxyethyl) phosphate,di(2-ethylhexyl) phosphate, mono(2-ethylhexyl) phosphate,tris(2-isooctyl) phosphate, tricresylphosphate, cresyldiphenylphosphate,trixylilphosphate, triphenylphosphate, triethyl phosphate,tri(2-chloroethyl)phosphate, or a mixture thereof.
 18. The process ofclaim 17, wherein the agent comprises a substance, polymer or moleculethat: is adapted to spontaneously form a nanometric film on a waterinterface of the aqueous phase/hydrophobic surface; has a solubility inwater ranging from 0.001% to 1%; has a relative permittivity less than80 but greater than a relative permittivity of the hydrophobic surface,or has a refractive index greater than 1.33 but less than a refractiveindex of the hydrophobic surface, has a water/agent surface tensionranging from 5 mN/m to 50 mN/m; and is a liquid at ambient temperaturewith a viscosity ranging from 1 mPa·s to 100 mPa·s.
 19. The process ofclaim 17, wherein the agent is adsorbed on an inert mineral support. 20.The process of claim 19, wherein the inert mineral support comprises asilica, an alumina, a silica-alumina, a silico-aluminate of sodium, acalcium silicate, a magnesium silicate, a zirconia, a magnesium oxide, acalcium oxide, a cerium oxide a titanium oxide, or a combinationthereof.
 21. The process of claim 17, wherein the liquid film comprisesan aqueous insoluble film forming polymer dispersion in water.
 22. Theprocess of claim 17, further comprising adding the agent directly to theliquid film in an amount ranging from 0.01 to 5% by dry weight of agentbased on the total weight of the composition of the liquid film.
 23. Theprocess of claim 22, wherein the amount of agent added ranges from 0.02to 1%.
 24. The process of claim 18, wherein the effective amount of theagent ranges from 5% to 95% of the a maximum solubility of the agent inwater.
 25. The process of claim 17, wherein the hydrophobic surfacecomprises PVC, polyethylenterphtalate, polycarbonate, polyamide,polyolefin, polyethylene, polypropylene, human skin, human hair, naturalfibers, synthetic fibers, crockery, metal objects, ceramics, or acombination thereof.
 26. The process of claim 17, further comprisingmodifying the aqueous phase by adding at least one organic or inorganicelectrolyte salt comprising monovalent or multivalent anions and/orcations.
 27. The process of claim 26, wherein the salt is added to aconcentration less than 0.1 wt % of the total weight of the aqueousphase.